Machine and method of forming sheet metal articles



March 26, 1968 w. D. ANDERS ON 3,374,519

MACHINE AND METHOD OF FORMING SHEET METAL ARTICLES Filed Aug. 30, 1965 3 Sheets-Sheet 1 l6 2| ma Hill-SINK INVENTOR. WARREN D. ANDERSON 2o BY JOHN P. CHANDLER HIS ATTORNEY.

March 26, 1968 W. D ANDERSON MACHINE AND METHOD OF FORMING SHEET METAL ARTICLES Fi led Aug. 50, 1965 3 Sheets-Sheet FIG.

FIG.

INVENTOR. WARREN D. ANDERSON JOHN P. CHANDLER HIS ATTORNEY.

March 26, 1968 w. o. ANDERSON MACHINE AND METHOD OF FORMING SHEET METAL ARTICLES 3 Sheets-Sheet 5 Filed Aug. 30, 1965 INVENTOR. WARREN D ANDERSON JOHN P. CHANDLER HIS ATTORNEY.

United States Patent Ofiice 3,374,519 Patented Mar. 26, 1958 3,374,519 MACHINE AND METHOD OF FORIVIING SHEET METAL ARTICLES Warren D. Anderson, Stamford, 'Conn., assignor to Norma-Hoifmann Bearings Company, Division of Universal American Corporation, a corporation of Delaware Filed Aug. 30, 1965, Ser. No. 483,644 9 Claims. (Cl. 29148.4)

ABSTRACT OF THE DISCLOSURE Method and apparatus for die forming ring-like Workpieces where the diameter of the piece gets smaller as successive operations are performed, which consists in forming radial tabs on the piece and placing them in radial slots, which are sufiiciently long to retain the tabs during the forming operations and finally cutting off the tabs.'

This invention relates to a novel method of locating and orienting a sheet metal workpiece relative to a carrier which moves it from one die forming operation to another. One use is in the making of retainers for ball bearings.

The usual method of making ball bearing retainers includes blanking the ring-like blanks by means of a first set of dies, then hand feeding the blanks, which have been deburred, as by a tumbling operation, to a second die set which produces the preliminary form for the ball pockets While at the same time reducing the diameter of the blank. Next, the blank is placed in a third die set which gives the ball pockets their final form. Finally, the blank is placed in a fourth die which pierces the rivet holes. In case the retainers are of the type which use sheet metal prongs to hold the assembly together, a somewhat similar set of operations is required.

The hand feeding is expensive and if the blank is placed in the die improperly, poor quality work is produced and the die set itself may be damaged and require expensive repairs. 7 Progressive dies reduce the amount of hand work, since a series of four or more dies are lined up in side-by-side relation and the blank is sheared out completely except for narrow struts which connect the blank to the skeleton of the strip. This skeleton then passes through the successive die stations and transports the blank from one die set to another.

This scheme has the disadvantage that it isnot possible to tumble and deburr the blank after the blanking operation. Also, it requires a very expensive die made to high precision in order to locate the blank properly in each successive die set,

' A third method is the use of a transfer mechanism, in which the individual die sets are arranged in line, side-byside, with a complicated mechanical system comprising arms and fingers which reciprocate in two directions to reach in and pick up the blank after each successive die operation, and transfer it to the next die in line. This system is expensive, complicated, slow in operation, and has given considerable trouble due to the fact that the fingers do not always securely hold the blank, and as a result, it is improperly placed in the succeeding die set and results in a smash-up of the dies. Conversely if the fingers grip the blank too tightly they deform it.

The principal object of the present invention is to provide an improved method which eliminates all of the foregoing difiiculties and results in a simple and practical method of transporting the blanks sequentially from one die set to another. It is also adaptable to existing die sets and thus eliminates the vast cost of a large number of new dies which is necessary if the radial move is made from the hand feeding system to the system of progressive dies or the transfer system listed above.

In the drawings:

FIG. 1 is a plan view of the machine of the present invention;

FIG. 2 is a broken section taken on line 2-2 of FIG. 1;

FIG. 3 is a broken section taken on line 33 of FIG. 1;

FIG. 4 is a broken section showing the turret raising means;

FIG. 5 is a broken plan view showing the motor drive for the turret;

FIG. 6 is a broken section taken on line 66 of FIG. 5;

FIG. 7 is a broken section showing the final die station;

FIG. 8 is a circuit diagram;

FIG. 9 illustrates a modification of the method wherein the blanks have straight line rather than rotary motion;

FIG. 10 is a plan view of a finished, conventional ball retainer made in accordance with the method of the present invention, 7

The apparatus shown in FIG. 1 includes a disc-like turret 10 which is intermittently rotatable by suitable motor driving means M to index the turret in a plurality of work stations where the blanks are sequentially operated upon. The turret is mounted on a vertical spindle 11 mounted in a bearing 13 and it has a plurality of through openings 12 of a size to receive the ring-like sheet metal blanks 14. A plurality of recesses 16 extend radially outwardly from each through opening and downwardly from the upper face of the turret about one half the thickness thereof, thus providing a recessed shelf 18 on which each radial tab on the flat ring-like blank is received and supported in a plane just below the top of the turret.

The blank has a plurality of generally rectangular tabs 19 which extend radially from the outer perimeter of the blank in spaced relation, three being shown in FIG. 1. The blanks are die stamped by a first set of dies in a previous blanking operation (not shown). The burrs and sharp corners are usually removed by tumbling. The blanks are now fed, one-by-one, either automatically or by hand to the position shown at the station I wherein the radial tabs 19 rest upon the shelves 18.

A more or less automatic blank feeding mechanism is shown in FIG. 2 which includes a magazine 19 to receive a stack of the flat blanks 14. The magazine is supported on a fixed bracket 20 adjacent to the turret and the blanks rest on an eccentric shelf 21 which is repositioned as to provide a span between it and the lower end of the magazine. An 'apertured plate 22 moves the lowermost blank off the magazine whence it drops. A solenoid D moves the sliding plate. Such feeds are well known in the art. The initial diameter of the blanks is shown as being only slightly less than the diameter of ening 12 in the turret. The turret is now rotated one increment which is in the case of the 4 station apparatus shown.

The blanking die is not shown, which die may be considered as the first die set, and when the formed blank with its radial tabs is dropped into the recess at station I the turret is ready to be indexed to station II. At station II a second die set 23 having an upper die 24 mounted in press ram 9 and a lower die 25, closes upon the blank while its radial tabs 19 are supported on the shelves 18. This die set, which has the usual aligning pins 26, is suitably mounted on a platform 27 and is able to perform its operation without interference from the turret, since the lower die is concentric with opening 12. This die set gives 'an undulating wavy shape to blank 14 and hence reduces the diameter of the ring-like blank. The radial tabs are thus set further towards the center as shown. The ball pockets 28 are separated by the flats 29 which are radially aligned with the tabs'19. The radial tabs thus provide accurate location and orientation of the formed blank relative to the turret, even though the blank diameter is changing.

While the forming operation is occurring at station II a second blank is deposited in the opening 12 at station I and as the partly formed blank is now indexed from station II to station III another flat blank is applied at station I and the initial blank is moved to station III where a third die set 30 closes and finishes the forming operation. The blank is now moved to station IV where a fourth set of dies 32 pierce the rivet holes and simultaneously shear off the radial tabs 19.

While the above method uses a rotary turret, the basic principle of using radial tabs in'radial recesses could be used with other types of transfer mechanism, for example the carrier for transporting the blanks might be a metal plate 33 shown in FIG. 9 attached to an endless chain 34 passing over suitable drive sprockets (not shown).

The hole 35 for the blank has the same'radial recesses 36 for the tab 19 of the blank.

The driver for the center shaft 11 includes a motor shown at .M in FIG. having a shaft 37 on which a Geneva wheel 38 is fast and as this driver rotates at a fixed speed its pin 39 passes into one of the 4 radial slots 40 of the driven member 42 and imparts increments of rotation to shaft 44 on which driver member 42 is fast.

Shaft 44 has a bevel gear 46 fast thereon which meshes with another bevel gear 48 slidable on shaft 11 and keyed thereto by key 50.

After the blank has been given its undulating'shape at station II, it is desirable to lift the blank out of the lower die so that the turret can be rotated to the next position and this is accomplished by 'a lever 52 pivoted on the frame at 54 and which has yoke 55 and roller 56 at its inner end engaging a plate 57 secured in the lower surface of turret 10. A pneumatic cylinder 58 moves the lever to raise the turret and the parts are timed to follow the act of raising the turret by rotating the same one increment to index the workpieces to the next station. At the final station IV, the upper die 60 in cooperation with the lower die 22 acts to shear the tab 19 from the completely formed blank and this die performs any other operation necessary for securing the pair of retainers together. These operations are not illustrated since they are so well known in the art but they may include punching rivet holes or preparing fingers which are bent over. FIG. shows the finished retainer 60 with pockets 62 and flat 64 with rivet holes 66.

A brief circuit diagram is shown in FIG. 8 only for the sake of completeness since any number of conventional circuits may be used.

While there have been described herein what are at present considered preferred embodiments of the invention, it will be obvious to those skilled in the art that many modifications and changes may be made therein without departing from the essence of the invention. It is therefore to be understood that the exemplary embodiments are illustrative and not restrictive of the invention, the scope of which is defined in the appended claims, and that all modifications that come within the meaning and range of equivalency of the claims are intended to be included therein.

What I claim is:

1. In a method of die forming ring-like ball bearing retainer blanks using a transfer system employing a carrier member for transporting sheet metal, retainer blanks from one die-forming station to another, the method of positioning said retainer blanks relative to said carrier member, which consists in providing each blank with radial tabs extending from its perimeter, then forming on the carrier member a plurality of matching radial recesses,

setting said tabs into said recesses, and finally shearing the radial tabs from the blank after the last contourforming operation has been performed.

2. In a method of die forming ring-like ball bearing retainer blanks using a dial transfer system employing a rotary carrier member for transporting sheet metal retainer blanks from one die-forming station to another, the method of positioning said retainer blanks relative to said carrier member, which consists in providing each blank with radial tabs extending from its perimeter, forming on the carrier member a plurality of matching radial recesses, setting said tabs into said recesses, and finally shearing the radial tabs from the blank after the last contour forming operation has been performed.

3. In a method of die forming ring-like ball bearing retainer blanks using a transfer system employing a carrier member for transporting ball bearing retainer blanks from one die-forming station to another, the method of positioning said retainer blanks relative to said carrier member, which consists in providing each blank with radial tabs extending from its perimeter, forming on the carrier member a plurality of matching radial recesses, setting said tabs into said recesses, and finally shearing the radial tabs from the blank after the last contour forming operation has been performed.

4. In a method of die forming ring-like ball bearing retainer blanks using a procedure of transporting a ring-like sheet metal retainer blank from one die forming station to another, which consists of providing tabs extending radially from the retainer blanks perimeter, depositing each blank on a rotatable turret having through openings to receive the blanks and radial recesses extending fromv the opening for receiving and supporting said tabs as the turret is intermittently rotated from one die station to another where die operations are sequentially performed on the blanks.

5. The method of forming retainers for ball bearings comprising the steps of die stamping a ring-like sheet metal blank with a plurality of spaced tabs extending radially from the outer perimeter thereof, then depositing the blank in one of several through openings in an inter mittently rotating turret having a plurality of work stations, said openings shaped to receive the blank and provided with radial recesses extending downwardly from the upper face of the turret, forming shelves to receive the tabs in supporting relation, rotating the turret to a second station where a die set closes and gives the blank its preliminary undulating form, said operation reducing the diameter of the blank, then advancing the blank to a third station when a set of dies closesand gives the ball pockets their final spherical form, then advancing the blank to a fourth station for a final die operation including shearing the tabs from the blank and then discharging the formed blank.

6. In combination with die forming apparatus, a transfer mechanism for transporting, from one die forming station to another, a sheet metal retainer blank having a plurality of tabs extending radially from its outer perimeter, a frame, a carrier member mounted for rotation on the frame and provided with a plurality of radial recesses,

matching said tabs and into which the tabs are placed to locate the blank relative to the carrier.

7. In combination with die forming apparatus, a trans fer machine for intermittently moving ring-like sheet metal retainer blanks to a plurality of Work station where die operations are sequentially performed on the blanks, which latter are provided with a plurality of tabs extending radially from their outer perimeters, said machine including a disc-like turret, a vertical spindle upon which the turret is mounted for rotation and a motor for intermittently rotating the turret to a plurality of work stations, said turret having, a plurality of openings equal to the number of work stations including a blank feeding station, said opening shaped to receive the initial fiat blank and having a plurality of radial recesses alignedwith the radial'tabs on the blanks and extending downwardly from the upper face of the turret a portion of its thickness and forming recessed shelves on which the blank tabs are supported, and a work performing die set at each station after the first.

8. In a method of die forming ring-like ball bearing retainer blanks using a transfer system employing a carrier member for transporting sheet metal retainer blanks from one die-forming station to another and wherein each blank has radial tabs extending from its perimeter, the method of positioning said blanks relative to said carrier member, which consists in forming on the carrier member a plurality of matching radial recesses, and setting said tabs into said recesses and moving the carrier member so as to position each blank at several work stations for sequential die operation to be performed thereon.

9. In a method of die forming ring-like ball bearing retainer blanks using a dial transfer system employing a rotary carrier member for transporting sheet metal retainer blanks from one die-forming station to another and wherein each blank has radial tabs extending from its perimeter, the method of positioning said blanks relative to said carrier member, which consists in forming on the carrier member a plurality of matching radial recesses, and setting said tabs into said recesses and rotating the carrier member so as to position each blank at several work stations for sequential die operation to be performed thereon.

References Cited UNITED STATES PATENTS 1,387,881 8/1921 Ringham 29-201 2,416,578 2/ 1947 Garden 29201 3,128,819 4/1964 Bachelet et a1 29-5l3 THOMAS H. EAGER, Primary Examiner. 

